Thursday, 21 January 2010

Rotary encoder for ATS transceiver series

This equipment is dedicated for an easier control of the popular mini-transceiver AT Sprint known by ham radio operators as ATS (series ATS-2, ATS-3, A, B, B.1 compatible). Originally the ATS has just four push buttons on the top cover and in combination with the paddle it is possible to send all commands to ATS including the tuning, scanning etc. After connecting the rotary encoder accessory module an easy tune, scan and other functions are available as same as on the big size desktop transceivers. Comfort and operation is much higher even with this mini transceiver.Description:
Some times ago my friend and colleague Petr (OK1RP) bough and built ATS transceiver. When he showed me how it works I saw that tuning is not very comfortable. I thought that would be nice to be able to control tuning with rotary encoder in the same way as it is possible on large desktop transceivers. Petr was very excited about this idea. We looked at the schematic and the idea of schematic was born in my had. I built first prototype and it worked quite well. And now you can see final version of the rotary encoder module.

The heart of the rotary encoder module is microcontroller Atmel ATtiny2313. The firmware in the microcontroller is watching the turning or pushing of the main tuning knob on the encoder module. According to movement of the tuning knob the microcontroller control three transistors which are connected in parallel with push buttons in ATS.

Block diagram of the rotary encoder

The rotary encoder consisting the main blocks as follows: microcontroller, encoder unit with knob, LED indicators, transistor switching circuit, voltage regulator and connector for connection with ATS.

Schematic of the rotary encoder kit

I designed the double side PCB. The size of the PCB is 38x36mm and it has two mounting holes. Really nice, isn't it.

Assembly diagram (top side)

Assembly diagram (bottom side)

Interconection with ATS:

For correct functionality of the rotary encoder module is necessary to connect five wires as follows:1) connect the GND of the ATS to the GND of the rotary encoder2) connect Vcc voltage from ATS board to rotary encoder board3) connect the push buttons MENU, UP and DOWN on the ATS board to the rotary encoder board

Rotary encoder pins description

The five wires cable should be used for interconnection between ATS and rotary encoder module. Due to this interconnection it is possible to easily disconnect encoder and use ATS alone as originally designed. On the ATS side the wires are soldered to push buttons pins, power supply and GND pins.

Interconnection between encoder and ATS transceiver

Control options:

Rotation 1 step to the left

- simulates pushing the button DOWN (tune down)

Rotation 1 step to the right
- simulates pushing the button UP (tune up)

Pushing the tuning knob long time- simulates pushing the button MENU long time (go to MENU)

Double click to the tuning knob- “tuning” mode is activated which is indicated by the both green LED's flashing. Encoder is waiting at this moment for the direction where to go to tune the transceiver. It can be done by simply rotation right/up or left/down of the main tuning knob. After setting the directions as mentioned the encoder simulates holding the push button up/down on the ATS to tune through the band without necessity to hold any button or knobs! We are talking about the automatic scanning through the band. The selected direction is indicated by the flashing of corresponding green LED. To stop the tuning through the band just press or rotate the tuning knob in any direction.

Conclusion:It took few months from first idea to the final version of the kit, but it was nice work with good result. I would like to thank you to OK1RP and OK1SA for support and testing of this kit. On the following pictures you can see one of the last version of the rotary encoder module on the professionally made PCB. Actually the last version is using 1206 size of resistors and capacitors instead of 0805 size for easier soldering. I will post photos with 1206 part soon in the next post where I will public step-by-step procedure how to assembly this kit (so stay tuned).

Ordering Information:Because I thought that this device could interest other ATS radio operators I made a kit with all parts including pre-programmed microcontroller and the PCB. If you would like to buy the kit, please contact me on my mail address diy4fun@gmail.com. The price of the kit is 25USD. The shipping is 5USD worldwide for one kit, 6USD for two kits and 7USD for three kits. I prefer PayPal for the payment and I'm sending the kits by standard postal service.